The present invention relates to improvements in an apparatus for and a method of making perforated adhesive tapes.
The present invention further relates to an apparatus for and a method of producing controlled perforations in an adhesive-coated porous web, and most particularly relates to an apparatus for and a method of utilizing controlled gas streams in order to produce desired perforation patterns in adhesive-coated porous webs.
The need for adhesive-backed tapes incorporating a myriad of relatively fine perforations for various applications, has been felt for a long time.
Cloth tapes comprising a porous backing of woven materials, such as cotton, or the like, and coated with a pressure-sensitive adhesive, have found wide applicability in both the medical and electrical fields.
In the medical field, adhesive-backed cloth tapes are widely used currently to mechanically retain bulky medical dressings or medical appliances used for therapeutic or monitoring purposes on the body of the patient.
In the electrical field, adhesive-backed non-conductive cloth tapes are used to isolate and/or insulate groupings of electrical wires or electrical components.
Adhesive-backed woven cloth tapes are preferred in many cases to tapes having nonwoven backings, because of their inherent greater tensile strength and elongation properties, which permit substantially more pressure to be applied to the tape without its stretching. Cloth tapes offer the additional advantage of being fairly easily tearable in a straight line, normally along or across one or another lines of the weave. This feature is especially desirable when scissors or other cutting implements are not readily available.
The presence of perforations in the adhesive-backed tapes which are produced by the apparatus and process of the present invention, will also facilitate the tearing factors discussed above in some applications.
In a medical setting, when it is expected that the adhesive-coated tape will be in place for an extended period of time, the use of perforations will enable this long term adhesion to be achieved by allowing moisture accumulated under the applied tape to readily evaporate.
The conventional prior art techniques designed to incorporate perforations in adhesive-backed tapes, have usually utilized an apparatus which embodies a perforating element carrying a plurality of needle-like points, or the equivalent, which are positioned so as to mechanically impinge upon the adhesive-backed tape during its manufacture shortly after the application of the adhesive coating thereon, so as to perforate both the tape web backing as well as the adhesive coating applied thereon.
One of the more serious drawbacks of such a prior art apparatus and method, has been the need to embody a means to insure the setting or hardening of the adhesive coating sufficiently rapidly in order to prevent a tape back flow thereon as the perforating needle-like points are withdrawn, that would then result in a closing off of the perforations.
A further drawback to the mentioned prior art devices, has been the need for incorporating a means to both automatically and continually clean the perforating needle-like points after each penetration of the tape backing material and the associated adhesive coating.
The applicant has thus surprisingly found that the instant invention, which utilizes a controlled or regulated gas flow pressure, as well as a precisely directed gas flow, results in a predetermined discrete perforation pattern in an adhesive-coated porous web, that further eliminates the above-described serious drawbacks found in the prior art techniques.